The proposed work is an exploration of the use of affinity methods for the assay of arachidonate metabolites and as physiological probes. We propose to extend current studies of polymer-tethered 15-(3H)-PGF2 alpha as a reagent for the assay of PGDH (an enzyme which metabolized prostaglandins) and the natural prostaglandins themselves. These studies should establish the general features of this new class of assays: competitive enzyme-affinity assays. Antisera grown to conjugates of prostacyclin and thromboxane analogs will be used as agonist traps in order to determine the roles of exogenous prostacyclin and thromboxane in phenomena such as platelet aggregation and endothelial cell migration and proliferation. A number of novel assays for prostacyclin are proposed. In one, hydrolysis in tritiated water will serve to induce the radiotracer so that scintillation counting will quantitate intact PGI2 levels. We also propose to synthesize (3H)-PGI2 at greater than 100 Ci/m mole and to use this material to search for specific receptors suitable for a receptor binding assay. Videofluorometry will be applied to the HPLC and TLC detection of prostaglandins bearing fluorescent markers. Videoradiometry is proposed for the scanning of TLC plates and the quantitation of tracers including 3H/14C ratio determinations without elution.